Radio signaling system



Dec. 8 1925 1.564.807

E. F. w. ALEXANDERSON R'Amo' smzumne svs'rsl Filed May 4, 1918 /0 Invent or Ernst 'F' W. Alexahderson,

, His fitter-nay.

Patented Dec. 8, 1925.

UNITED; STAT-Es ERNST F. w. ALnXAnnEnson, onsonnnncrany, nnwyonx, assrenon TQGENE L ELECTRIC COMPANY, A CORPORATION or new YORK; I

RADIO sIenAL ne sYs'rnM.

Application filer! May a,

To all whom it may concern:

Be it known that I, ERNST F. W. Amaze ANnnnso a citizen of the, United States, residing at Schenectady, county of Schenectady, State of New York, have invented certain new and useful Improvements" in Radio Signaling Systems, of which the following is a specification. I

My present invention relates to radio signaling systems and particularly to "a transmitting system in which continuous radio frequency current is employed for produc-- ing signals. 1

When a source of continuous radiov frequency current such as an oscillating arc has been employed for signaling purposes, it has been the usual practice'to produce signals by varying the tuning of the antenna and thereby varying the frequency or wave length of the transmitted wave. 7 This method has one marked disadvantage over a system in which thesignal is produced entirely by intensity variations of the trans mitted wave, in that itmay result in interference with other stations which operate on a slightly different wave length.

The object of my invention is to provide a transmitting system in which the signals transmitted will be produced entirely by variations in the intensity of the antenna current. I V

In carrying my invention into effect I make use of a controlling device which is based on the principle of magnetic saturation. Devices of this type, which I term magnetic amplifiers, are described in my prior U. S. Patent No. 1,206,643. Assuming that the antenna is the fundamental tuned circuit, I have found that a magnetic amplifier may to advantage be made a part of a second tuned circuit which is asso ciated with the antenna circuit, and that by this arrangement a much wider range of change in impedance may be produced than when the amplifier is directly included in the antenna circuit. The magnetic amplifier of the general type described in my 191a. Serial No. 232,589.

upon thetuning of thesystem, there are certain difiicultieswhich must be overcome. A more specific ob ect of my present 1nvent-ion is to provide a system in which these difficulties will be-obviated. Since the fre- H quency of-the current depends upon the ca.

pacity andinductance of the circuit, it is.

taneously in such a way that intensity va riations' may be produced without introducing frequency variations. the inductance and capacity of the antenna circuit should remain substantially constant. If a magnetic amplifier were introduced in series with'the antenna, as shown in my prior patent above referred to, this would not be the case, since in the operation of the device a wide variation of resistance is always accompanied by a wide variation of inductance, the variations, depending upon the degree of saturation produced by the controlling current. If a second tuned circuit alone is used a similar difficulty will exist. In order to overcome these difiiculties, I provide athird tuned circuit which may be designated as 'a tertiary circuit, the antenna tuning being the primary and the tuning of the magnetic amplifier proper being the secondary. Neg- In other words,

lecting for a moment thefantenna tuning,

the combined controlling device which I.

provide and which is'made up of one or more magnetic amplifiers, will of itself have a double tunedcharacteristic, one of the tuning points being the original tuning ClI'-,

cuit of the magnetic amplifier, the other. tuning point being produced by the combination of the magnetic amplifier circuit and.

other devices which make up the tertiary tuning circuit. Broadly speaking, a condition of tuning is one where the inductance and capacity of a circuit neutralize each otherat a certain frequency, that is, the complete circuit is apparently a non-reactive circuit for that frequency. A double tuned circuit xbecomes non-reactive under two sets. of conditions. These condltlons are usually defined by saying that the circuit becomes non-reactive at two frequencies. Inasmuch as the object of the present inventionis to design a system which operates only at. a single frequency, the nature of the invention may be best explained by saying that the combined controlling circuit is double tuned with reference to diiferent degrees of saturation of-the magnetic amplifier in-v volved, rather than with reference to two different frequencies. I11 other words, the object is to produce a combined circuit which becomes non-reactive at two difierent values of the controlling current used for saturating the magnetic amplifier unit or units involved. I

7 be less than the effective resistance of the antenna, while at the same time the effective resistance of the circuit will be varied by an amount much greater than the effective resistance of the antenna. By the term effective resistance as used herein, I mean the electromotive force in phase, with the current at the specified frequency, required to force one ampere of current through the circuit.-

In another form of my invention in which two magnetic amplifiers are employed forming two secondary circuits, the tertiary circuit is formed by a. combination of the two secondary circuits. In this case the controlling circuit is substantially non-reactive throughout the entire operating range.

The novel features which I believe to be characteristic of my invention are set forth withparticularity in the appended claims. The invention itself, however, both as to its organization and method of operation will best be understood by reference to the fol lowing. description talren in Connection with the accompanyingdrawing in which Figure 1 shows the first modification of my invention above refer-red to, and Figs. 2 and 3, respectively, show tvo different circuit connections whereby the second modification of my invention may be carried into eifect.

As indicated in the drawings, the source of continuous radio frequency current employed in my transmitting system comprises the are 1, which is supplied with direct current for its operation from the direct current generator 2, the usual inductances 3 and 4 being included in the circuit. The arc 1, in the system indicated-in Fig. 1, is connected in series with. the antenna 5, which is provided withthe usual tuning inductance (3. In series in the antenna circuitI provide a variable inductance or magnetic amplifier 7 of the. general type described in my U. S. Patent No. 1,206,643. In the specific forn'i here shown the device comprises windings 8 and 9 which are in par allel in the antenna circuit and the current for saturating the magnetic core is derived from direct current generator 10, being supplied to the'windings 8 and 9 in series by means of a key 11. The amplifier is shunted by a capacity 12 and resistance 13. i If the condenser 12 is given such a value as, to neutralize the inductance of amplifier 7 at the operating frequency when its core is not saturated thecontrol circuit becomes non-reactive and the resistance of the portion of the circuit which includes the amplifier will depend only upon the value of the resistance l3. If new a saturating current is applied to the windings of amplifier 7. the inductance will change and the resistance of the antenna circuit will no longer be determined by the value of resistance 13 but will depend upon the value of the inductance of the amplifier. lVhile the actual value of the amplifier inductance will gradually decrease, its 'eii'ect as an inductance in the antenna circuit will increase with an in crease in the saturation current from Zero up to a maximum value and will then :decrease until it is neutralized by the series condenser 14:. The inductive effect of the amplifier in the antenna circuit will then be zero but the resistance of the antenna circuitwill be much less than when the core is unsaturated. In this case the combination of the magnetic amplifier? with the series condenser 14: forms the secondary tuned circuitand the capacity 12 in combination with the amplifier 7 forms the tertiary tuned circuit.

I have found that there is a fairly wide range between the 'two points where the effect of the inductance of the amplifier in the antenna circuit is Zero, over which its value does not vary enough to materially affect the natural frequency of the antenna circuit. In order to take advantage of this range a constant saturatingrcurrent may be supplied to the amplifier windings of such a value as'to bring the value of the amplifier inductance in the antenna circuit to a point in the desired operating, range where the antenna resistance is high. The value of this current, which may be supplied by generator 10, may be adjusted by means of the variable resistance 15. The circuit which supplies the controlling current is also preferably so adjusted that when thekey 11 is closed to short circuit the resistance 15 the valueof the amplifier inductance in the an tenna circuit will still be within the desired range but the antenna resistance will be greatly decreased. The two values of satnrationcurrent may be 'so selected that the antenna inductance will be the same when the key is pressed as whenitis open and hence the natural frequency. of theantenna' at the same time theantenna resistance; may

be varied sufficiently-to secure an e-lfectiye modulation of the current.

In the arrangement shown in Fig. 2, condenser 16 is employed in shunt tothearc, and in shunt tot-he condenser 16, I provide a second variable inductance, or magnetic amplifier 17, of the same type asdeyice 7. When, the controlling circuit isin the condition shown in the drawing the key 11 being closed at 18,. the intensity-of. the current in the antenna 5 will be a minimum. Under theseconditions the inductance of amplifier 17 is small and the inductance of amplitier 7 is large. 'The inductance of amplifier 7 is neutralized by the capacity 12 in shunt therewith in-the same way as in Fig. 1, when the key 11 is open, so that the secondary circuit formed by amplifier and the inductance 12 becomes substantially non-react ve but fo ms high mpe a in the antenna oircuit,.- A t Same time the inductance of amplifier 17 is neutralized by the large capacity 16 so that the. resultant secondary circuit also becomes substantially non-reactive and the loop 16, T17, 14, forms an absorption circuit; When it is desired to transmit telegraphic signals key 11 is operated to close the contact at 19 and open the contact at 18. The inductance of 7 then becomes small and is neutralized by the capacity'l G in series therewith. Consequently the control circuit is again in effect nonreactivebutthe effective resistance is much less. than when the key is closed at contact 18. V v I v lVhen the key 11 makes contact at 18, the resulting impedance for the circuit formed by amplifier 17 and capacity 14; as well as that circuit formed by amplifier 7 and ca pacity 12 is substantially non-reactive. IVhen the key is shifted to make contact at 19 the resultant impedance of the circuit formed by amplifier 17 and capacity 14 becomes inductive and the resultant impedance of the circuit formed by amplifier 7 r and capacity 12 becomes capacltive.

The resultant inductive impedance of the first circuit, however, neutralizes the resultant capacity impedance of the second circuit.

The arrangement which I have, illustrated in Fig. 3 differs from that shown inFig. 2 in that the capacity 16 instead of being in shunt with the arc is in, series-ftherewith. 11 p fe ie f. t syst lmwe 'er. wi

be suhstantiallythesame that ofthe one shown in Fig.2 with the eXc-epticn' that: In

this case as soon as the impedance of the c0nt'r01--. y' tembecomes arge there w l be a marked falling off in the arcicllrlent, whereas in the arrangement shown in Fig. 2

the arc current will be diverted to the sectimes of 17 is neutralized, by capacity 16 capacity 12. Hence both ofthese loops 16, 14,17 and 12,. 7- offer ahigh impedance to the flow of current in the antenna. lVhen h y 11 is i ed he 11 6, 7, becomes in effect an inductive impedance and the loop 12, 7 becomesa capacity impedance. The resultant inductive impedance of loop 16,, 14, 17 is neutralized by the ret-ant cap yi mp dance of 0 1 2; 7 which is in series therewith.

the flow of current inthe antenna.

andv the inductance of 7-is neutralized by V I V The ooinbination of the two loops therefore becomes non-reactive and offers a low impedance to In utilizing my amplifiers in theimanner 7 described it is necessary thatcon densieiys 20 be inserted intheclosed circuit formed by the windings9, and 10. These condensers should have such value. asto' offer a lowinr pedance to the high frequency current but a high impedance to the -.control1ing current.

While I have shown and described three 7 different ways in which my invention may be carried into effect, I do not wish to be limitedto the particular circuit arrangements shown as it will be' apparent that many variations may be made the variousdetails and in the form of H18 apparatus usedwithout departing from the scope of myinvention asset forth in thefappended claims. For example, while I have shown and described my invention with .particular'reference to theuseof an oscillating arc asa source of radio frequency energy, its utility is by no means limited tothis part cular current source as other sources of supply may equally 'wellbe employed-in carrying my invention into effect.

What I claim as new and desire to; secure by Letters Patent of the United States,

1. The combination in a radio signaling system of an antenna circuit snp'plied by a so 7 key 11 is in the position shown the inducing the inductance to produce a substantial change in the effective resistance of the control system and at the same tiine maintain its resultant rcactance substantially constant,

2/The combination inja radio signaling system of an antenna supplied by a source of continuous radio frequency current, means for varying the amplitude of the current in said antenna comprisinga magnetic controlling device, and means for varying effective resistance of said amplitude varying means by a value greater than the effective resistance of the antenna while the accompanying variations of reactance are less than the effective resistance of the antenna. o

3. The combinationin a signaling system of an arc generator, an absorption circuit and a signaling circuit associated therewith and a single control means for 'simulta neously varying in oppositesenses one of the constants of each of the two circuits.

4, The combination in a signaling system of an arc generator, an absorption circuit and a signaling circuit associated therewith and a single control meansfor'simulta neously varying in opposite senses one of the constants of each of the two circuits, said means being adapt-ed to substantially prevent the flow of current in the signaling circuit during the intervals between signals. 5. Means for controlling the flow of radio; frequency current in an electric circuit comprising a variable inductance having a shunt and a series capacity associated therewith, the capacities being so chosen that at one value of the inductance it is neutralized by the series capacity at a de sired frequency and at a second value of the inductance it is neutralized by the shunt capacity at the same frequency,.the values of the different constants being solchosen that the resultant reactance of the combi- I nation being substantially the same with either value of the inductance butthe effective resistance of the combination being much greater at the second value of the inductance than at the first.

6. The combination in a signaling system of an'arc generator, anabso-rption cirshunt capacity; the second circuit being so proportioned that it becomes resonant to the desired frequencyv one value ofthe variable inductance and the third circuit being so proportioned that it :becomes resonant to the desired frequency a t'a second value of the variable inductance, the values of the different constants being so chosen that the resultant reactanceof the combination being substantially the same with either value of the inductance but the effective resistance of-the combination being much greater at the second value of the inductance than at the first. f

8. The combination in a signaling system of an arc generator, an absorption circuit ii'eous'ly increasing the efiective resistance of the absorption circuitand decreasing the effective resistance of the signaling circuit.

9'. The method of operating a radiating antenna system-comprising a variable inductance which is common to'two oscillating circuits which consists in varying the value of said'inductance andthereby producing a substantial variation in the efiective resistance of'the system and at; the same time maintaining the reactance of the system substantiallyconstant;

v10; The combination in aradio signaling system ofan antenna suppliedby a source of continuous radio frequency current, an iron core inductance in series in said antenna circuit, a similar inductance in shunt to a capacity in said antenna circuit and means for varying the saturation of the cores of said inductances in such a way as to simultaneously vary both the inductive and capacity impedance of the antenna circuit.

11. The combination in a radio signaling system of an antenna suppliedby a source of continuous radio frequency current, a series inductance in said antenna circuit having a normally saturated magnetic core, a second inductance in shunt to a capacity in said antenna circuit, said second inductance having a normally unsaturated iron core and means for simultaneously varying the saturation of the cores ofsaid inductances to simultaneously vary both the inductive and capacity impedance of the antenna circuit.

12. The combination in a radio signaling system ofan antenna supplied by current from an oscillating arc system, a series inductance in said antenna circuit having a normally saturated magnetic core, a second inductance in shuntto a capacity in said antenna circuit, said second inductance having a normally unsaturated iron core and means for simultaneously desaturating the core of the first inductance and saturating the core of the second inductance.

13. The combination in a radio signaling System'of an antenna suppliedby current a normally unsaturated-iron core andmeans for simultaneously desa-tura'tin-g the core of the first inductance andsaturating' the core of the second inductance," said second inductance being so proportioned that when its core is saturated it will neutralize the capacity which it shunts.

The combination in a radio signaling system of an antenna circuit suppl ed by-a source of continuous 'radio frequency cur rent, said antenna circuit comprising two parts, one of which has a resultant inductive impedance and the other aresultant capacity impedance and means for simultaneously varying by means of a controlling current the characteristics of said parts of the-circuit in such a Way thatjthechange in effective inductive impedance {of the first part neutralizes the change in the effective capacity impedance of the second part. 7 Y

15. The method of controlling the flow of current in an oscillating circuit which comprises two parts, one of which has a resultant inductive impedance and the other a resultant capacity impedance which consists in varying simultaneously by means of a controlling current the characteristics of said parts of the circuit so that the changein effective, inductive impedance of the-first part neutralizes the change in the effective capacity impedance of the vsecond part.

16. The method'of controlling the flow of current in an antenna circuit which comprises an iron core inductance which consists in varying the permeability of said iron core and thereby varying the effective resistance of the antenna circuit while maintaining its natural frequency substantially constant.

17 The combination in a radio signaling maintaining the natural frequency of the antenna circuit substantially constant.

18. The combination in a radio signaling system of a source of continuous radio free quency current, a signaling circuit and an absorption circuit associated therewith, and means for simultaneously varying in' opposite senses one of the constants of each of the two circuits while maintaining the natural frequency of the system substantially constant.

19. The method of operating a signaling system comprising an arc generator which consists in impressing a signaling current v said genera-tonwupon: an absorption circuit and asignaling circuit and simultaneously varying the opposite senselby V a common control "inean's-one of the constants of each of the two circuits. f 20. The method ogf cperating signaling system whichconsists in impressing asignaling current upon an -absorption"circuit and a signaling circuit and simultaneously "vary- ,ing in opposite senses one of :the constants of each of the two circuits, and=at the same time maintainin'g the natural frequency of the system substantiallyconstant. f

211 The method-of operating a signali i -E system comprising an arc generatorwh c consists in impressing a slgnal ng currentfrom said generator upon an absorption circuit. "and la signaling; circuit and simultaneously varying in opposite senses bya common control means one of the constants of each ofthe two circuits'to such an extent as to substantially prevent the flow of current in the absorption circuit duringlthe signaling periods and to substantially prevent the fiow of current in the signaling circuit during the intervals between signals.

22. The method of operating a signaling system comprising an arc generator which consists in impressing a signaling current from said generator upon an absorption circuit and a signaling circuit and rsimultaneously varying in opposite senses by a common control means one of the constants of each of the two circuits to such an extent as to substantially :prevent the flow of current in the signalingcircuit during the intervals between signals. s

23. The method of operating a signaling I system which consists in impressing asig naling current upon an absorption circuit and a signaling circuit and simultaneously varying in opposite senses the effective resistances of each of the two circuits and atand a signaling circuit and simultaneously increasing the effective reslstance of the ab sorption circuit and decreasing the efiective resistance of the signaling circuit and atthe' sametime maintaining the natural frequency of the system substantially constant.

25,111" a radio telegraphy transmission system, a source of-oscillations, a radiating circuit containing inductance connected to said source, a shunt oscillatory circuit con taining inductance connected around said source, means for varying the'resistance of the radiating circuit, and means for varying the resistance of the shunt circuit in response to the operation of the radiating circuit resistance varying means.

26. In a radio telegraphy transmission system, asource of oscillations, a radiating circuit connected to said source, a shunt oscillatory circuit, connected around said source, means for varying the resistance of the radiating circuit so as to alter substan- I tially its ability to respond to the oscilla tions of the source, and means for varying the resistance of the shunt circuit in re- 27. In a'radio V telegraphy" transmission sy'stemhaving an are for producing oscilla-- tions' and a radiatingcircuit adapted to be suppliedby the arc, means for signaling comprising means for varying a characteristic of the radiating circuit such that there I is. a tendency to vary the energy lossin the radiating circuit, a by-pass circuit, and means forvarylng the characteristlcs of this by-pass circuit in responseto the variation in the radiating circuit Wherebythe arc 0scillates substantially entirely on one or the other of said circuits. v p p 28. The combination with a source of oscillatory, currents, of a tuned-Work circuitconnected tobe energized therefrom, a tunedabsorbing circuit connected in shunt-to said Work circuit, each of said circuits including a damping device, and a single means operable tofvary in opposite directions the proportions of said damping devices.

29. In an electrical system, a normally oscillatory ork circuit, means included therein adaptedto render the same non-oscillatory, a normally oscillatory idling circuit including means adapted torender the same",

non-oscillatory, and a single means oper-" able to render one of said meanscii'ective and the other of said means iioirefiective, andvice versaa a In Witness whereof, I have hereunto set my vhand this 2nd dayjof May, 1918.;

ERNSTF. W. ALEXANDERSQN. p 

